title: Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle.
abstract: OBJECTIVE
  To examine the androgen response to exercise in women under conditions of high (H) and low (L) estrogen (E2) levels.
  
  
  METHODS
  Ten exercise trained eumenorrheic women (mean ± SD: 20.0 ± 2.2 years, 58.7 ± 8.3 kg, 22.3 ± 4.9 % body fat, VO2max = 50.7 ± 9.0 mL/kg/min) completed a 60 min treadmill run at ~70 % of VO2max during both the mid-follicular (L-E2, 69.7 ± 7.3 % VO2max) and mid-luteal (H-E2, 67.6 ± 7.9 % VO2max) phases of their menstrual cycle. Blood samples were taken pre-exercise (PRE), immediately post (POST), and 30 min into recovery (30R) from exercise and analyzed for total testosterone using ELISA assays. Results were analyzed using repeated measures ANOVA.
  
  
  RESULTS
  Testosterone responses were (mean ± SD: L-E2, pre = 1.41 ± 0.21, post = 1.86 ± 0.21, 30R = 1.75 ± 0.32 nmol/L; H-E2, pre = 1.27 ± 0.23, post = 2.43 ± 0.56, 30R = 1.69 ± 0.34 nmol/L). Statistical analysis indicated no significant interaction existed between high and low estrogen conditions across the blood sampling times (p = 0.138). However, a main effect occurred for exercise (p < 0.004) with the post-testosterone concentration being greater than pre, although pre vs. 30R was not different (p > 0.05). All testosterone hormonal concentrations immediately post-exercise greatly exceeded the level of hemoconcentration observed during the L-E2 and H-E2 exercise sessions.
  
  
  CONCLUSIONS
  Prolonged aerobic exercise induces short-term elevations in testosterone in trained eumenorrheic women, which appears unrelated to estrogen levels and menstrual cycle phase. These increases may occur due to either increased androgen production and/or decreased degradation rates of the hormone, and are not solely the result of plasma fluid shifts from the exercise.
authors.affiliation: Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, CB # 8700 Fetzer Hall, Chapel Hill, NC 27599, USA. coleary@live.unc.edu
authors.forename: C B
authors.initials: CB
authors.lastname: O'Leary
authors.forename: C
authors.initials: C
authors.lastname: Lehman
authors.forename: K
authors.initials: K
authors.lastname: Koltun
authors.forename: A
authors.initials: A
authors.lastname: Smith-Ryan
authors.forename: A C
authors.initials: AC
authors.lastname: Hackney
mesh_terms: D000328:Adult; D004967:Estrogens / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008597:Menstrual Cycle / Q000097:blood*; D013739:Testosterone / Q000097:blood*; D055815:Young Adult
chemical_list: D004967:Estrogens; D013739:Testosterone